Fallen
by BunnyDip
Summary: Marinette's class is on a hiking/camping trip, but what happens when Adrien stands up for Marinette with almost everything Chloe throws at the poor girl and Chloe gets sick of it, and accidentally pushes Marinette down the hole of Mt. Ebott and Adrien jumps down to protect her from the fall. Rated t for violence and maybe some cussing. Adrienette/ LadyNoir
1. Chapter 1

Fallen

(Y-Yo! THis is my first cross-over and first Miraculous Ladybug and Undertale fanfic. Plagg and Tikki will be in it, but they will only be in it to give advice or what not, There may be times when Chat Noir or Ladybug appear, but not really, and of course an Identity reveal. U-umm... Please enjoy, I own only my crappy writing skills...)

Long ago, two races ruled over the Earth: Humans and Monsters

One day, war broke out among the two races.

After a long battle, the humans were victorious.

They sealed the Monsters underground with a magic spell.

Many years later...

[Mt. Ebott, 201X]

Legends say that those who climb the mountain never return.

Marinette may be the luckiest girl on earth! She was on a camping/hiking trip with her class and they were climbing a mountain, uhhh crap what was it's name again? Oh right!, Mt. Ebott! She looked ahead and stared at the love of her life, Adrien Agreste, the star model with beautiful blonde styled hair and strikingly beautiful green eyes, if he were to look in her bluebell ones she would most likely melt. "Adrikens!" the voice made Marinette want to vomit, sadly she was also the world's most unlucky girl. She continued walking, following the group, in their four man team they had Marinette, Adrien, Chloe, and Sabrina. So she was dragging behind in the back as she followed them. Adrien would slow his pace to a slow walk at times which Marinette took as he was trying to slow down for her so she wouldn't be left behind, which she was grateful for. But Chloe would catch on and grab Adrien's hand and pull him ahead, leaving Marinette behind, again. Marinette looked up and stared at the sun then her watch, "Hey! It's time for lunch!" she called out to the group. She frowned when she saw she was too far behind. She held her bag closer and ran to catch up.

When she caught up she smiled, "Hey, it's time for l-lunch." she cursed mentally when Adrien stared directly in her eyes, to show her she had his attention, causing her to stutter. Adrien smiled "Alright cool." he said and looked around and pointed at a tree, "How about we eat over there in the shade?" he suggested. Marinette nodded and walked over to the tree and set the blanket up. Chloe scoffed and walked over, "Sabrina, my pillow." she ordered. The ginger nodded and opened her bag and set down a flat pillow for Chloe. Marinette frowned sightly but did nothing. Adrien sat beside Marinette and smiled, "So who was in charge of bringing food?" he asked, looking around. Marinette blushed and held her hand up slightly and pulled out the tub-a-wares of food and paper bag with sandwiches. "Did you bring caviar?" Chloe asked obnoxiously. Marinette looked up and frowned, "No... Why would I bring caviar?" she asked. "Because it's what I want to eat." Chloe retorted. Marinette's frown deepened, "Sorry Chloe, if you want caviar then go find a river and pickle the fish roe." she said and looked at Adrien, "I pack PB&J sandwiches, is that okay?" she asked blushing. Adrien smiled, "Sure, I don't mind." he said, he hardly got to eat peanut butter and Jelly because it wasn't 'fancy' enough or something. Marinette smiled, but it didn't last for long cause Chloe scoffed, "I'm not eating that commoner food!" she nearly screeched, or it seemed like one in Marinette's head. Marinette frowned, "Then you would be fine with not eating at all." she snapped back, she was getting annoyed with Chloe's 'Oh, I'm so much better than you cause my Daddy is the mayor of Paris' attitude. Adrien looked at Chloe, "Chloe if you weren't going to eat what Marinette packed then you should have brought your own meal." he said and turned to Marinette and looked at the tub-a-ware and tilted his head it was a fairly large container and in the shape of a circle. He didn't ask questions, since he figured Marinette will tell them what was in it sooner or later. Marinette passed the sandwiches out and began eating. She was so nervous at the moment and swore if Adrien looked at her she would choke. Adrien smile at the taste, he tasted something different than usual in the bread but ignored it since it gave the sandwich a brilliant taste.

When they finished with their meals Marinette opened the tub-a-ware and revealed a cinnamon apple pie. "I baked it last night..." she said in a shy voice. Adrien's eyes widened, "It smells amazing Marinette!" he praised happily. He felt shuffling against his chest and wanted to frown, but didn't so Marinette wouldn't get discouraged. Marinette blushed heavily, "T-Thank you." she said and pulled out the plastic plates. Carefully she cut the pie with a plastic knife. She put the slices on the plates and passed them out, even giving Chloe one. Before Adrien could take a bite he heard Chloe spit the pie out and knock his out of hand. He looks up at Chloe with a glare. "What the heck is your problem?" he asked angrily. Chloe scoffed, "You should be thanking me Adrikins, that tasted like crap." she said and glared at Marinette, who's head lowered. Adrien stood up and glared at Sabrina who was about to throw her slice to the ground, "Don't you dare drop that. If you are going to waste it give it to me." He said. Sabrina nodded and place the pie in his hands. Adrien took his fork and cut off a piece of the pie and took a bite, his eyes widened and he looked at Marinette, "Marinette this taste amazing! No that's not even good would put every baker in France to shame!" he praised. Marinette looked up shocked, her eyes watered happily, she ducked her head and blushed heavily. Adrien looked at Chloe, "I didn't know how stupid your taste buds could be Chloe." he said and finished the slice of pie. He help Marinette clean up and stood up, "We should hurry, we are supposed to meet up with everyone later." he said and began walking, followed by the rest of the girls. Marinette's face was blood red, her eyes sparkled with tears she refused to let fall. 'He loved it...He loved my pie..' She thought and she felt like running forever. She heard a light giggle and she looked down and smiled at Tikki, who's head was slightly sticking out of the purse she carried.

When they reached to top of the mountain the sat down to take a break, they were the first there. Marinette eyed the giant hole, it wouldn't be safe to call this a camping space, what if someone fell? She stood up and walked over to the hole and peered in, "..." Kneeling down she pulled a pin out of her bag and dropped it. "1..2..3..4...5...6...7...8...9...10..." She stopped counting her eyes wide, "Holy cow..." Standing up she began to move away from the hole, until she felt someone behind her, turning around she saw a flash of blonde, but frowned when the hair was long and in a pony tail. "Hey Chloe can you move please?" she asked, she wanted to get away from the hole, asap. Chloe narrowed her eyes. "No, All day Adrien has been giving you attention, he's been sticking up for you. Well, I'm sick of it." She said angrily, and before Marinette could comprehend what happened, she felt wind and Chloe moving farther away from her, no, she was falling, her eyes wide with terror. Chloe's eyes were wide as well, what did she just do!? She screamed in her head. Marinette did the only thing she could think of, scream. Adrien ran over and saw Chloe standing where Marinette was and he ran over. He looked at Chloe and then down the hole. Marinette grabbed onto a root quickly letting out a wail of pain as her hands ripped at the sharp roots and her body tugged on them slowing her from her fall. Adrien's eyes widened, "Marinette!" he yelled panicked. "Hang on!" He looked around, he couldn't transform here, there was no way. He looked down and saw Marinette losing her grip. He glared at Chloe and grabbed the front of her shirt, fury and rage in his green eyes, "What have you done!?" he seethed and shoved Chloe away, causing the girl to lose her balance and fall backwards towards the ground behind her. He turned around and when he did, he saw Marinette's hand slip and she fell. A flash of red seemed to appear in his eels and he blinked, he felt his heart shatter, his eyes made it look like it was Ladybug falling, and he jumped, his mind seeing only ladybug falling in the place of Marinette, "M'lady." he called out reaching out to Marinette. Marinette couldn't hear him due to the wind in her ears, but to her it seemed like he mouthed, 'Marinette' and she reached out to grab his hand. Adrien tried to push himself forward, their hands slapped each other a few times before they grabbed onto each other. Adrien pulled Marinette to his chest and hugged her tightly, flipping themselves over so he would hit the ground, though he no longer saw his lady, but Marinette. Hugging her tightly he closed his eyes, "I'll protect you, princess." he muttered into Marinette's ear. Marinette clung to Adrien as the fell her eyes shut. And then, Darkness filled her mind.

/ Aw crud it's all crappy... I hope you guys like it so far, I'm sorry if they are OOC. I'll try to do better in the future. Gahh! I'm super embarrassed. Uh, follow, fav, or review if you like. It would encourage me to continue. / W-Well bye! Have a nice night.


	2. Chapter 2

H-Hi! I want to say Thank you to Siren,Lady Psychopath, Lizzie2145, Slam'in Burst, AsherTurntech, for following and/or favoriting my story! I'm so so grateful and i nearly started crying! A-Anyway! On to the story!

When Marinette opened her eyes she regretted it, shutting her eyes quickly, she moved to put her hand on her head and realized her arm wouldn't move. She opened her eyes completely and was met with the face of Adrien Agreste. Her eyes widened and she touched his face with the arm that was willing to move and gently rubbed his cheek, "Adrien! Adrien!" she called, begging him to open her eyes when memories of what happened flashed into her head.

Adrien opened his eyes and winced, he saw Marinette and felt her hands on his face "Marinette? What happened?" He asked sitting up, but stopped when he saw her wince painfully. He looked her over and saw her arm hanging limply. "Marinette! Your arm!" He exclaimed, shocked. Marinette smiled, "I'm fine, really. From what I can tell it's dislocated." she said and stood up moving off of him. She looked up to see how far they fell but her eyes widened, "Adrien...we fell...right?" she asked hesitantly. Adrien looked at Marinette confused, "Yeah why?" He asked and watched Marinette's right arm point up wards, making him look up out of curiosity and he froze. "What!?" The roof of what should have been a gaping hole was covered by Crystals. Marinette helped Adrien up and he gasped in pain. "Gah!" he yelped painfully and clung to Marinette. Marinette grabbed Adrien helping him stand. "Come on Adrien, You can lean on me." she said and the two began walking through the cave, down the only path available praying to find a way out.

Adrien had one arm over Marinette's shoulder and used his other arm to hold out his phone for light. "I'm sorry about all this Marinette..." he said limping down the tunnel. Marinette looked at him, "What are you talking about? This is my fault, if only I didn't ruffle Chloe's feathers." she said walking being careful of her arm. They walked through the tunnel they saw a light. When they reached the light they froze, sitting in the grass was a buttercup and it was... Smiling? Marinette and Adrien looked at each other and then the flower. They walked forward and froze, "Howdy!" the flower spoke. "Adrien... Am I going crazy?" Marinette asked softly. Adrien shook his head, I was about to ask the same.

"I'm Flowey. Flowey the Flower!" The buttercup now known as Flowey, continued. Marinette and Adrien blinked and then looked at each other, knowing it definitely just spoke. "I-I'm Marinette..." Marinette greeted cautiously. Adrien bowed his head slightly, "And I'm Adrien." The flower smiled happily, "hmmm, You're new to the Underground aren't cha?" The two nodded. "Golly! You must be so confused." again a nod from them. Marinette looked around the cave, she couldn't see anything other than the flower and the ground in front of them. She squinted her eyes and saw a crevice in the wall, looking like a way out, but it was ridiculously dark. "Someone ought to teach you how things work down here!" Marinette looked back at the flower and felt shuffling in her bag, 'Tikki!' she thought and put her hand on her bag and smiled happily, she was so scared she forgot about the kwami.

Adrien looked at Marinette, "You okay?" he asked softly. He received a nod and a soft smile, he blushed and looked away when he saw how close their faces were."I guess little old me will have to do." The flower spoke again catching the two teen's attention. "Ready? Here we go!"and then the world around them went dark, except the flower and two yellow bars in front of them. Marinette looked around curiously and then she looked at her chest and where her heart was there was a little red heart. "...!" Marinette blinked and touched it, warmth filled her hand and made her feel calm, kind, strong, and brave. Adrien looked down at his and saw a small green heart. He touch his as well, and felt a lukewarm feeling through his body, he felt strong, proud, and the need to protect someone. He removed his hand and looked at Marinette's heart. It was a pretty red, one that made him want to never see it dull in color. Marinette smiled and looked at Adrien with a smile, the struggling in the bag seemed to get frantic, but Marinette put her hand on the bag again to calm the kwami. "See that heart? That is your SOUL. The very culmination of your being!" And as if on cue the two hearts floated away from their chest and levitated in the air in front of them. "Your SOUL starts off weak, but you can grow strong if you gain a lot of LV." Marinette opened her mouth to speak, but before she could start, the flower interrupted her. "What's LV stand for you ask? Why, LOVE, of course!" Marinette smiled at the innocence this little flower had and got excited to gain some, 'LOVE'. Adrien would have taken a step back if he wasn't leaning on the small dark blue haired girl. "You want some LOVE, don't you?" Marinette nodded smiling. Adrien looked in his jacket coat and saw Plagg, no.. Plagg was hiding... He got a really bad feeling. "Don't worry! I'll share some with you!" Flowey winked. Marinette smiled and nodded. Adrien held tightly to Marinette, she was being too trusting, and it worried him. "Down here love is shared through... Little white..." Adrien furrowed his brow at Flowey's face he seemed nervous and avoided eye contact, but Marinette seemed not to notice as her eyes were fixated on the little white oval orbs floating above Flowey. " 'friendliness pellets.'" Adrien narrowed his eyes getting ready to move, "Are you ready? Move around! Get as many as you can!" The pellets moved close to them and Marinette reached out for them, "Marinette no!" a small voice screamed, and Marinette hissed in pain as the pellets hit her. Adrien couldn't dodge as he was holding onto Marinette and let out a gasp of pain. His skin felt like it was on fire, the pellets burned his skin. He flicked them off with his hand and helped Marinette. Marinette closed her eyes in pain and looked at Adrien in relief. A small red, bug? No, Kwami flew out of her bag and hugged Marinette's face, "Marinette you need to listen when I'm trying to help you!" The kwami scolded, Adrien's eyes widened and he blinked but then remembered the threat. He turned away and saw Flowey falter a bit after seeing the kwami, but then grinned evilly and began laughing. "You IDIOts! In THis WorlD It'S KilL Or bE KIllED." It laughed. Marinette's eyes widened and she hugged Tikki close to her chest. Adrien growled, he was about to transform to protect Marinette, but he fell letting out a small yell of pain as he hit the ground. "WHy WOuLD AnyoNE PaSS uP an OppoRtuniTY like THIS!?" Marinette turned towards Adrien, "Adrien!" she yelled and grabbed his arm and helped him up, She looked around, she couldn't transform, her arm was useless and she needed to support Adrien! What were they going to do!? "DIE!" FLowey screeched and the pellets surrounded them. Marinette's eyes widened and she hugged Adrien close, "I'm so so sorry." she cried as the pellets got closer. Tikki narrowed her eyes, "Marinette! Don't give up!" the kwami cheered urgently. Adrien bit his lip, "Plagg, Claws out-" he didn't finish the sentence, cause when the pellets were about to touch them, they disappeared. "WHAT!?" Flowey once again screeched, and a ball of fire sent the flower flying. "What a terrible creature! To torment such poor innocent children such as yourselves." a GOAT!? Said. Adrien narrowed his eyes at the goat. Marinette fell to her knees, and blacked out.

When Marinette awoke she found herself in a purple room and Adrien was leaning over her worried. Marinette jumped up slamming their heads against each other. Adrien grabbed his head and leaned forward, pressing his head against the ground, "owwww." the two teens had the same reaction, holding their heads and muttering 'ow'. THe two looked at each other and began laughing, "hahahaha!" when the laughter died down and they smiled, "Sorry about that, Adrien." she said and then froze, she looked at her arm and realized it was healed, "What happened!? How long have I been out?" She asked shocked. Adrien smiled, "Toriel healed you." he explained and pointed to the goat. Marinette smiled and stood up, when she was standing straight she bowed her head, "Thank you so much." she said and stood up straight. Adrien stood up and smiled, the room was bright so while Marinette was sleeping he noticed her outfit was tattered, but now that she was standing, he saw the full extent of the tattered clothing, the back of her shirt was ripped and he even saw the back of her bra. He blushed heavily and turned away, he walked forward so he wasn't standing behind her. Toriel smiled, "Hello child, I'm Toriel the caretaker of the ruins. If you come with me I can lead you to a safe Marinette looked at Adrien and he nodded, "It's fine, we can trust her." he assured her and began walking.

Adrien looked in his button up white shirt, which too was torn and tattered, and looked at Tikki and Plagg, he felt guilty so he stopped and looked at Marinette, "Marinette, Here." he said and placed the kwami in Marinette's hand, "Sorry... I wanted to ask Tikki a few things." he said softly. Marinette's eyes widened, "Tikki!" she said shocked and hugged the kwami. Tikki smiled happily and returned the hug, "I'm sorry Marinette, but Adrien knows now." she said softly. Marinette frowned and she looked at Adrien who wasn't meeting her eyes. "It's okay..." she said and walked over to Adrien, she grabbed his hands and smiled, "Just don't tell anyone, okay? Chat will kill you if you knew it and he didn't." She said and gave him a wink. Adrien blushed heavily seeing Marinette show a bit of her Ladybug side. Toriel stopped at the top of the stairs across the room, "Hurry children." she said with a patient smile. Adrien nodded and the two turned around and blinked, there was a yellow light... The two looked at Toriel, "What is that light?" Adrien asked curiously. Toriel looked up, "Oh, these are crystals that shine brightly lighting the way." Toriel obviously didn't know what they were talking about.

Marinette ran forward and touched the light, and the entire world froze, except her and Adrien, the coloring was the same, just everything was froze. Adrien walked forward and knelt down, out of curiosity he picked up a leaf and let go of it and it froze in the middle of the air. "Whoa..." He muttered and stood up. Marinette looked at the leaf then the light, and as if on cue, a deep voice filled her and Adrien's mind " **The Shadow of The Ruins Looms Above, Filling You With Determination. Would you like to save?"** then two buttons appeared in front of them, one saying yes, the other no. Marinette looked at Adrien, "Is this like a game?" she asked confused. Adrien shrugged and pushed 'yes'. Then the world went back into play and the leaf fell, catching Toriel's attention, "hmm?" but she lost her train of thought and smiled. Adrien and Marinette walked over to Toriel followed by Adrien. Toriel led them to the next room and smiled, "Welcome to your new home, innocent ones." Marinette caught the sentence and grabbed her arm tightly, not liking this information. "Allow me to educate you on the operation of the RUINS." Toriel turned away and walked over 4 pressure plates and flipped a switch, which opened the door across the room. Toriel walked back over and smiled "The Ruins are filled with many puzzles." Marinette and Adrien nodded before they continued to another room, this room was long, what caught Marinette's attention was the 3 switches on the wall. "I want you to flip the switches marked on the wall." After flipping the switches spikes sunk into the ground making it available to cross. The next room was a plain room with a Dummy. "As humans in the underground, monsters may attack you. You will need to be prepared for these situations." The two blinked, again, not words Marinette wanted to hear. "Worry not! The process is fairly easy. When you encounter a monster, you will go into battle mode. You should simply talk to the monster and stall for time until I come and solve the conflict."

Adrien nodded, though it was different than normal where when they fought akumas, but if fighting them meant they got LV, or LOVE. Then he wanted to avoid that at all cost, he didn't want to become like that flower. "Now practice talking to the Dummy." the two teens looked at each other confused, neither wanting to go first. Marinette sighed and walked forward, "Hello," she heard Adrien snicker which caused her to blush furiously, "I'm Marinette. It's nice to meet you." she said and looked at Adrien, "Your turn." she said and walked over to the door blushing. She noticed her stutter went away, well this was no time to be stuttering, so it made sense. Adrien stuck his tongue out at Marinette and walked over to the Dummy, "Yo! What's up man? How are you today?" He asked, he felt so stupid, talking to something that couldn't talk. Marinette smiled and looked at Toriel, who seemed pleased with them and they continued onto the next this room was slightly different, It caught Marinette's attention that the ground had a path but unlike the others, it didn't lead from the entrance of the room to the exit, but from wall to wall. They continued through the room and came to a stop in the hallway.

Marinette looked at the sign and attempted to read it, but sadly, to no avail. Toriel smiled, "Come along children." she said, bringing Marinette's attention to her. Marinette walked away from the sign and the next room had spikes covering the floor. Toriel smiled, "I was going to make you solve this puzzle, but it seems to difficult. Take a hold of my hand." she said. Adrien took Toriel's paw and held out his hand for Marinette. Marinette stared at this hand for what seemed to be the longest time, but was actually only a few seconds, before she took his hand, blushing crazily. Adrien smiled and looked at Toriel, "Alright, we are ready Toriel." Toriel nodded and began walking through the spikes. Marinette and Adrien's eyes widened, but they continued walking with her and Adrien hesitated before stepping through the spikes only to see they were illusions. "Whoa." he said following Toriel. Toriel smiled, "Have you two not seen magic?" Marinette looked up, "Well actually, we have but nothing like for traps and what not." She said and when they crossed the puzzle they headed on to the next room.

"You two have done excellently thus far, but now I must ask you to complete a difficult task. I need you walk down to the end of the room without me." Toriel smiled and turned away, running away quickly. Adrien and Marinette looked at each other and headed after her . "I can't believe you're Ladybug." he said shocked and smiled at her. Marinette frowned and blushed, "Y-yeah… " She looked at her hands. Adrien looked at her and frowned, "L-Marinette…. What's wrong?" Adrien asked. Marinette looked at Adrien, "... I… I don't want you to only notice me because of someone I pretend to be," she said sadly. Adrien looked at her and stopped moving, "Marinette, I jumped down here for you. Yes, I felt like I was going to lose Ladybug if I didn't jump. But all in all, I knew, that I was jumping down here, for the girl who sits behind me in class, who stutters and blushes like crazy near me. The girl who has a sharp tongue when people wrong another or wrong her. Marinette you are Marinette and one of my closest friends." Adrien said smiling. Marinette looked behind her and gave him a smile, "Thanks Adrien." she said and continued walking. They reach the end of the room and saw Toriel, "You did excellent my children. Now there was a reason behind this, I must ask you to stay here and not leave this room. I have to run off and do some errands. There are puzzles up ahead that i have yet to explain. Now then I'll give you both a phone.." she said and reached into her pocket. Marinette smiled, "Don't worry Toriel, we have phones." she said pulling out her phone. Adrien nodded and pulled out his phone as well. "See?" Toriel smiled and nodded, "Alright children," Toriel looked at their phones confused, "C-Can you put your numbers into my phone? Your phones seem…." Marinette nodded and took Toriel's phone. It took her a second to figure out how it worked but then put both hers and Adrien's number in Toriel's phone, also putting Toriel's number into hers. "Alright, wait here." Toriel said and ran off, Marinette opened her book bag and looked at the contents "Hey the pie is still in decent condition…" Marinette said taking the pie from her bag. Adrien smiled, "Cool." he said sitting down. The two sat there for awhile, talking laughing, poking fun, and eating the pie. But after awhile the two got bored just sitting there. "Hey Marinette, do you want to continue to the next room?" Adrien asked looking at her. Marinette looked at Adrien, "I know Toriel told we needed to wait, but it's boring just waiting here." Adrien continued. Marinette thought about it for a bit before she nodded, "Alright." she agreed and stood up. Adrien smiled and rose to his feet. Then the two headed on the the next room.

 **I'm sorry if this feels more slapped together TT^TT and if the reveal wasn't as great and dramatic as you hoped. I don't really have much skill so…. But i hope you liked it.**


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